The worst food poisoning I ever had was a few days after returning from a weekend vacation with friends. When I finally dragged myself out of the bathroom, an email was waiting for me: “Is everybody else feeling okay? I know our dinner together was a few days ago so I’m sure it’s not that, but I just wanted to check.”

We never found out what food was the culprit, but there was only one meal we all shared and every adult there came down with vomiting and diarrhea about two days later. That’s classic food poisoning. But sometimes the situation is less clear. How do you know when you have food poisoning versus a run-of-the-mill stomach bug, and what should you do about it?

Food Poisoning Is Really Just Another Stomach Bug

The truth is, there’s no medical difference between “food poisoning” and other diarrheal illnesses. The same germs that cause food poisoning are also common causes of stomach flu or traveler’s diarrhea.

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In all of these cases, some virus or bacterium, or perhaps even a parasite, took the fecal-oral route from (sorry) somebody’s butt into your mouth. From the germ’s point of view, it’s a wonderful way to travel: you get eaten, trigger the person’s body to spew from either or both ends, then do your best to stick to surfaces that they or somebody else might touch.

Other organisms follow a similar route, but usually not with such ruthless efficiency. Maybe some fecal bacteria from the farm (say, E. coli) got onto some beef and into a grinder, and from there spread to several packages of hamburger meat. You leave the meat out too long—maybe in a cooler at a picnic that wasn’t as cool as it should have been—and the bacteria multiply. Then you cook the burger, but not all the way since you like them rare. Your immune system kills off most of the bacteria, but not quite enough. The bacteria make a toxin that makes you sick. Mission completed.

Don’t Blame Your Last Meal

If you ate with friends and all of you come down with vomiting or diarrhea at the same time, there’s a good chance there was something wrong with that meal. But sometimes you can’t track it down so neatly and it’s hard to know where exactly the culprit came from.

So if you can’t always blame your last meal, who should you blame? It turns out there’s a pretty big window of opportunity, depending on what exactly made you sick. Norovirus will live in your body for 1 to 3 days before you show symptoms; that time is known as the incubation period. Campylobacter, common in poultry, takes 2-5 days. Clostridium perfringens may strike the same day, within 8-16 hours. E. coli takes up to three days, although the nastier forms may take as long as a week. Salmonella is another quick one, striking in as little as 6 hours or up to 2 days. And then Listeria (which is mild in adults but can cause miscarriage or stillbirth if a pregnant woman contracts it) will cause stomach-bug symptoms within the first few days but show its more serious complications weeks later. The FDA has a handy chart here.

Take Care of Yourself, and Clean Up

To keep from perpetuating that fecal-oral route, be aware of the germs you’re probably spraying all over your bathroom. If you can isolate yourself from family or roommates, do that—for example, now would be a good time for your kid to spend the night at Grandma’s.

One of the common complications from food poisoning is dehydration, so drink water and consider other liquids when you’re ready, like Gatorade or ginger ale or soup. It’s normal to not feel like eating for a day or two. You may want to ease back into eating with simple, bland foods like crackers.

Signs of severe dehydration, including severe weakness or dizziness and inability to pee

Any neurological symptoms like blurry vision, tingling, or muscle weakness

Treatment is likely to consist of IV fluids to counter dehydration, and if your food poisoning came from a bacterial source, you may be given antibiotics. It’s important to seek help if you’re at high risk of complications. This includes pregnant women (because of the risks from Listeria, among others), small children (who are more prone to kidney damage from E. coli), or anyone who is elderly or has a condition that weakens their immune system.

Should You Report It?

If you end up going to the hospital with suspected food poisoning, your provider will probably report the case to the local health department, where investigators can piece together reports to figure out if a particular restaurant or store was the source of an outbreak. But what if you’re just puking on your own? I asked Stephen Morse, a professor of epidemiology at Columbia University:

I think it’s a good idea to contact your local health department, especially if you think others could possibly have gotten it too. If it was a party, picnic, or similar event, then the affected people may well have been talking to each other and may know whether more than one person in the group is sick. These investigations are pretty routine for larger health departments, and usually one-time events (the spoiled potato salad, for example), but health departments often like to know about them just in case they are part of a larger issue (for example, Salmonella in a batch of a commercial product). Even more important if you think it was from a restaurant, that should definitely be checked out by the health department. Health departments are generally very careful and discreet about restaurant investigations, but they want to know because it may mean to expect more cases, and (depending on the source) might be able to prevent future cases.

There is a list of health departments by state here, but you’re better off starting with your city or county’s health department (Google it). In some cases, it’s hard for individuals to report their own illness, because the health department is expecting reports from hospitals and labs. Still, it’s worth looking up; many departments encourage individuals to make reports, especially if you can trace back your illness to a particular restaurant.

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If you think you got sick from a packaged product, check the lists of recalls and alerts from the FDA, and consider reporting the product if it’s not already on the list. The agency moves at a glacial pace—yesterday they recalled a bad batch of frozen vegetables produced a year and a half ago. But still, better than nothing.

Prevent It Next Time

It’s impossible to fully protect yourself from food poisoning, but you can improve your chances by cooking and handling food properly. Spoiled leftovers may not always taste or smell bad, so the rule there is “When in doubt, throw it out.” Still Tasty is a good go-to database for figuring out how long is too long for something to be left in the fridge. (You may even be pleasantly surprised—some condiments are good for months.)

Cook food properly. Temperature is a better gauge than color when you’re working with meat. Keep raw meats separate from cooked foods, and don’t let anything sit in the “danger zone” for more than two hours. That’s the temperature range in between fridge temperature and piping hot. Fully cooking food will kill bacteria and inactivate many bacterial toxins, so it’s a good rule of thumb for making sure food is safe to eat—but if you suspect a food has gone bad already, reheating it won’t guarantee it’s safe. That’s because a few toxins, like the ones from Staphylococcus aureus, can survive cooking. Read up on proper food handling, and stay safe.